import java.util.AbstractSet;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;

class PropertiesAsMap extends AbstractMap<String, String> {

    private final Map<Object, Object> properties;

    PropertiesAsMap(Map<Object, Object> properties) {
        this.properties = properties;
    }

    @Override
    public Set<Entry<String, String>> entrySet() {

import java.util.AbstractSet;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;

class PropertiesAsMap extends AbstractMap<String, String> {

    private final Map<Object, Object> properties;

    PropertiesAsMap(Map<Object, Object> properties) {
        this.properties = properties;
    }

    @Override
    public Set<Entry<String, String>> entrySet() {

    @Test
    void testPropertiesAsMap() {
        Properties props = new Properties();
        props.setProperty("foo1", "bar1");
        props.setProperty("foo2", "bar2");
        PropertiesAsMap pam = new PropertiesAsMap(props);
        assertEquals(2, pam.size());
        Set<Entry<String, String>> set = pam.entrySet();
        assertNotNull(set);
        assertEquals(2, set.size());

    @Override
    public Map<String, String> getUserProperties() {
        return Collections.unmodifiableMap(new PropertiesAsMap(getMavenSession().getUserProperties()));
    }

    @Nonnull
    @Override
    public Map<String, String> getSystemProperties() {
        return Collections.unmodifiableMap(new PropertiesAsMap(getMavenSession().getSystemProperties()));
    }

    @Nonnull
    @Override

            properties.setProperty(key, value);
        }
    }

    @Override
    public Map<String, String> getProperties(Project project) {
        return Collections.unmodifiableMap(
                new PropertiesAsMap(((DefaultProject) project).getProject().getProperties()));
    }

    @Override
    public Optional<Project> getExecutionProject(Project project) {
        // Session keep tracks of the Project per project id,